In a head-to-head match-up, Christie fairs best against Clinton, but trails the former secretary of State 47 percent to 41 percent. In the same poll from April, Clinton edged Christie by 3 percentage points, 46 percent to 43 percent.

Clinton and Christie are two of the most popular political figures in the country.

According to a Quinnipiac University study released earlier this month, Clinton has a 55 percent favorability rating, while 38 percent of voters had an unfavorable view. Christie has a 45 percent favorability rating and 18 percent unfavorable. The New Jersey governor is also viewed favorably by a plurality of Democrats by a margin of 41 percent to 19 percent.

None of the potential candidates have publicly committed to a 2016 run. However, Ready for Hillary, a super-PAC pushing the former New York senator to run, is loaded with former Obama campaign activists.

The Marist-McClatchy poll of 1,204 adults was conducted between July 15-18 and has a 3.1 percentage point margin of error.